This invention relates to wrenches and hand tools, and more particularly, it relates to pipe wrenches and bar clamping mechanisms wherein it is desired to grip an object firmly, but wherein the tools are not specialized into so many unit sizes. Such tools are adjustable so that a number of different sizes of pipes or objects may be grasped by their jaws. Some pipe wrenches may have the ability to grasp pipes or objects as thin as ¼″ or ⅛″ wide or having a diameter of that dimension, on the one hand, and as thick as 5″ or more on the other. One difficulty with such tools is that the adjustment typically consumes time and may require two hands to manipulate. The familiar operating nut used with pipe wrenches, in accordance with U.S. Pat. No. 737,847, may require one hand to hold the wrench and the other to operate the nut, thereby increasing or decreasing the distance between the open jaws. More importantly, adjusting the opening between the jaws of the wrench is a very time-consuming operation.
Some wrenches provide a trigger-type mechanism to advance a jaw and thus clamp or restrain a workpiece or object. In these tools, exemplified by U.S. Pat. Nos. 5,005,449, 5,009,134, and 5,222,420, a trigger-type mechanism or holder is provided. These mechanisms, however, are cumbersome and awkward, and are meant much more for holding an object in place than in manipulating the object. Furthermore, they are not designed nor are they convenient for fast, one-handed operation, since these wrenches consume time in adjusting and manipulating. By manipulating is meant the action of tightening or loosening a pipe, a pipe nut, or other rotatable object, wherein a considerable force may be applied to the adjustable pipe wrench, and for which the embodiments in the above patents are not suitable. What is needed is a wrench that is both suitable for one-handed operation and does not require a great deal of time to adjust the opening of the wrench.